Studies on the Endocrine CJlands 25i) 



Effects lton thI:: Kat of Removal of Tuvkoid and Pai'.athviioids; 

 AND OF Thyroid and Pauathyhoid Administhation. 



Durini; a preliniinary period a diet consistin*; of a mixture of minced 

 lean meat and crround rusks in the proportion of 60 per cent, and 

 40 per cent, respective!}' had been employed, a sufficient amount of water 

 being added to make the mixture into a soft paste. But subsequently 

 (at the commencement of thyroid and parathyroid feeding) the meat 

 was omitted, rusks and water having by then been definitely adopted 

 as the standard diet. 



The rats were divided into three groups, A, B, and C. Group A con- 

 sisted of five normal male adult animals and was used as a control; group 

 B of five parathyroidectomised males (operated upon February 8, 1916); 

 and group C of three thyroidectomised males (operated on February 9, 

 1916). The animals belonging to each group were kept in the same cage, 

 and all three ca^es were close together in the same room and under the 

 same conditions of temperature. No special symptoms appeared to be 

 produced either by the parathyroidectomy or the thyroidectomy during 

 the period of observation.^ On March 24 one rat in each group was 

 killed and examined. This animal will be called No. 1. 



Microscopic Appearances of the Normal Rat's Pancreas 

 and the Changes produced by Parathyroidectomy and 

 by Thyroidectomy. 



No. 1 rat of A group (unoperated). Weight of animal 255 grm. All 

 the organs are normal. 



(a) The Normal Pancreas. , 



The pancreas has been examined not only in rat No. 1 of A group, but 

 in a large number of other normal rats, both male and female (pregnant 

 and non-pregnant), young and full-grown, so that the following description 

 of the normal pancreas is a general one. 



Under the microscope sections of the normal rat pancreas 

 (figs. 1-5 and Plate I., A) show alveoli which are approximately equal 

 in size. Most of the cells are rounded-angular and are also of fairly 

 equal size, although there are a certain number of small cells inter- 

 mingled with the others. The outer zone of the cells is usually 

 narrower than the inner : it exhibits striations w^hen carefully 

 examined under a high powder. It is stained by hsematoxylin more 

 deeply than the inner zone, and it is also stained of a faint blue 

 colour by Mallory's and Muir's stains. The inner zone is relatively 

 wide, occupying the greater part of the cell. It is only very faintly 

 stained by ha^matoxylin alone ; its granules are coloured by eosin. 

 The cell-nuclei do not generally vary greatly in size (5/x to 6'2/x), 



1 It is well known that rats resist the effects of total thyroparathyroidectomy for a 

 prolonged period. 



